Weekly Report from the Bellingen Covid-19 Clinic: Dr Trevor Cheney

Dr Trevor Cheney gives his weekly report from the Bellingen Shire Covid-19 Clinic

Dear Bellingen Shire

1 December 2020

 

I would like to consider a hot topic.

Firstly: Our Covid19 risk locally? Same as the rest of the State  -the risk is from someone unknowingly being infected from outside the jurisdiction and coming to visit or coming home.  This is the only source of cases now in NSW for most of the last month.  The Health Department is a little anxious that they are still getting traces of Covid19 found in Sewage treatment plants around the Greater Sydney and Bateman’s Bay area, but no one knows whether this is just dead remnants or fresh from someone still shedding.

South Australia’s evolving crisis is again instructive to us all.  The news media is reporting every blow and puff so I won’t reiterate the current state of play.  I only want to replay the same tune we have had on the old stereo turntable all along – that this is a long way from over, that a virus can pop up unexpectedly, that we must continue to be alert.  Keep our masks and response plans and attitudes sharp and ready.  If there is a case found locally then we all respond real quickly.  And we make sure all friends, family and neighbours (including any you know who don’t have good English) understand that we all need to jump.

Until the vaccine trials are completed or we have real good treatment options, the only things that have worked have been border control, quarantine, shut downs and personal protection.

Yes there continue to be Happy announcements about the vaccine progress.  Unfortunately each of these are followed by less fizzy, sobering admissions of emerging problems with each technology or strategy.  This is not bad news, or conspiracy.  It is simply, as predicted from the start, the nature of the science evolving.  We still will not see a real availability in Aust till some time next year.

A recent conference was reporting a keynote discussion on protocols for “Long Covid” Syndrome.  Lots of questions, no answers yet.  At least this syndrome is being widely acknowledged, although some experts want to put it down to a form of PTSD. I think that reasoning’s flawed.

In South Australia they are also dealing with the challenges of managing behaviours in a heat wave, trying to get testing clinics in the outdoors when people can’t be in the outdoors, and maybe then dealing with fire.

So the new hot topic is Heat.  Certain lucky folk on the Urunga Foreshore and the Beautiful Dorrigo plateau may have missed the singular experience in Bellingen last weekend of 42*.  We are very lucky to live in a time when the weather bureau can warn us of the impending heat wave, to have time to prepare. So prepare we must.

It was interesting on this morning’s news hearing one of the office bearers of the College of Emergency Medicine talking about elevating heat injury to the fore in emergency training. I had always noticed that heat injuries tend to be one of the last chapters in emergency textbooks, almost as a rare afterthought.  She stated that the incidence is growing and is expected now to be a common presentation in EDs

It is easy for new generations who have grown up with aircon and shopping malls, or in temperate countries, to not have a deep sense of what heat can do.  Life has adapted to most environments very successfully.   There are “thermophiles” – bacteria that can live around under water volcanos at boiling temperatures, no oxygen, using chemical energy to thrive. There is even a critter that looks like a multi legged bear that has survived on spacecraft, presenting an ethical dilemma for the excitable types talking of colonising other planets.

Humans have mechanisms that many other animals do not, and these have contributed to our domination of most niches on the planet, from the poles to the equatorial deserts.  One of the most effective is profuse sweating.  There are marathon races in USA deserts, with slightly shorter marathons in Wales , Scotland, New Zealand, pitting humans against horses.  At 22 miles it is neck and neck.  The longer the race the better the humans do.  And it is our ability to shed excess heat, then recover, that wins an endurance challenge.  IF you’ve adapted!

That said, like any good adaption or opportunity, you can overcome your advantage by bad decisions. Remember the old saying “mad dogs and Englishmen go out in the midday sun”.  In Aus we do that all the time. Our indigenous citizens have adapted to that environment.  The modern Australian – working more often than not in an indoor/office environment – certainly has not.

When we lived in the Pilbara of Northwest WA I once recorded 50* under the shade beside our house. There were teams of fellas (curiously mostly from the Balkans) who repaired the famous iron ore rail tracks, where they often recorded temperatures beside the track of 60*!  We had aircon.  They had guts!

But they could and did adapt.  It can take around 2 weeks to acclimatise to a move to a tropical zone.  You first note lethargy and a very salty tasting sweat. The salt you lose can contribute to headaches and fatigue.  If done well with replacement of fluid and salts (remember when health staff talk of salts we mean potassium, and magnesium and not just table salt –sodium chloride) your sweat glands then start producing mainly water, which evaporates, taking excess heat with it.

Now here is an essential curiosity about the chemistry of water.  When water molecules get warm they become agitated.  But the heat at a molecular level is not uniform.   Some molecules get lots hotter than their neighbours, till reaching the energy level to leave the puddle -taking considerable heat energy with them.  This is a principle of evaporative air conditioning.  In dry places like SA, WA , inland NSW, you can drop the temperature of the house quickly by 10*, even with open doors, by blowing air through wet material, eg straw or hessian. It was the principle of the old outback “Coolgardie Safe” for fridgerating meat and butter before there were refrigerators.

Of course in the subtropical haven of the lowlands of Bellingen Shire moisture = mould.

A bigger “of course” is that you need to have access to adequate clean water!  Same deal for bodies.

A really important life lesson that I hope is still taught in high school PE or equivalent is how bodies lose or gain heat.

You gain heat from :

-Radiation – direct heat from fires or the sun, your car motor (or a hot Bod);

-Chemical release  -the burning of energy when you exercise  – called metabolism (even at rest or asleep there is the “basal metabolic rate”);

-Ingesting it – eg a hot drink;

-Friction- can be enough to burn flesh – I have seen some nasty rope burns.

-Conduction, ie a hot object touching directly on the skin.

-Convection, hot air blows onto your skin from, say, a fire or rock directly delivering energy to the skin, or even into your lungs.

 

You can shed excess (or lose precious) heat with:

  • Radiation- which can be obstructed by clothes or reflective materials;
  • Evaporation – sweat directly vaporising off your skin, and often forgotten, in the fully saturated hot air you breathe out;
  • Conduction your hot skin pouring heat into ice packs in the armpits and groin – or directly into cool water;
  • Convection – ie a cloud of hot air settles around your body, but moving air brings in some a little less hot, carrying away the heated air.
  • Voiding – passing out heated urine or other secretions, which are replaced by a cooler liquid again, which you will then fill with heat.

 

Convection and evaporation are critically our advantage and explain why an adapted body can survive at 37* even when the ambient temp is 40*.  But you need water.

Various texts categorise heat injuries (apart from burns) in stages – heat cramps, heat exhaustion, heat stroke.

There is a nice little coloured chart from Queensland Health that you could google and put on your fridge for this summer.

 

Now I must reiterate – most of us are not heat adapted!, And a heat wave means  that despite your best intentions, you will not have been heat adapted for times like last weekend.   So this is really personal.

The most vulnerable are:

– The old – because adaptations don’t work well and some of our medications that keep people alive interfere with adaptation;

– Those on medications;

– Babies – there is much less distance from the hot skin to the core, and they lose water very quickly;

– People on fluid restrictions or with heart or kidney disease;

– People who take drugs like cocaine or amphetamines;

– People, or kids, or pets, sitting in cars – cars are like a magnifying glass.

 

We do so well, and then suddenly the systems fail.  Then our organs fail. Everyone who has been a cook knows that heat is used to change the chemistry and structure in food.  You can cook an egg in under 60*.  Oils (fats) melt.  Our own muscles effectively melt, and then clog your kidneys with gooey myoglobin. That’s the red stuff   in muscles containing iron that moves oxygen into muscle cells to the troponin, which is little hinged hooks that actually do the moving work of a muscle.

Someone who is starting to suffer from heat exhaustion will move slow and may make poor decisions from the lethargy.  Once a person moves on to a state of heatstroke, they become confused, dizzy, unsteady and are not able to make themselves safe.  This is a life-threatening emergency, which needs a bystander to jump quickly, get them out of the heat, and call an ambulance.

I treated a young fella some years ago in an inland town who decided to train early for the football season. With no preparation, he decided to run up and down the water tower, cursing himself for not being tough enough to do it fast.  He presented with muscle cramps.  The level of myoglobin in his urine was through the roof!  His muscles were literally dissolving and washing into his kidneys, which were then failing as they were clogged with the proteinaceous goo, so did not get adequate oxygen. He survived with lots of hydration.  He did not play football that year!

This starts happening with a body temp of only 40*.

This is a letter, not a text book, and the details are systematically better presented in some Health publications.  So please, your homework is to look up a chart with the early signs of heat injury, stick it up somewhere for the summer, think how you will access enough water, think how you will keep touch with your oldies.

Also may I say that, given the fuel load that dried out last weekend around our unburnt parts, check your fire equipment and readiness and plan again now.  That is what we spent Saturday doing.

And yes, being overheated or dehydrated seems to make you higher risk for contracting Covid19 if it is in the air, and also more likely to get complications!

As always this is one little smouldering perspective.  Please check any detail with your own  “hot stuff”  GP.

 

Dr Trevor Cheney

 

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